Alnico poles over alnico bar?

Al Walker

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OK, so, I'm experimenting with some pickups I have hanging around. Just for fun. Can you put alnico pole magnets over a bar magnet? Alnico 3 over alnico 5, alnico 2 0ver alnico 5, or other combos. What is the result. I'm also thinking of making pole magnet humbuckers with mixed alnicos. Your thoughts?
Thanks.
 

DarrellV

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Can you put alnico pole magnets over a bar magnet?
As long as the polarity matches. If not, you'll get no or weak signal. To what advantage, I'm not sure since they both do the same thing to magnetize the string...

Alnico 3 over alnico 5, alnico 2 0ver alnico 5, or other combos.
Again, match polarity and the stronger mag will reinforce the weaker one.

I did a similar mod on my old Shaw bridge. I put a ceramic bar mag under the base plate to strengthen the weak signal from the bridge Shaw. The stronger pull made its way to the pole screws and their pull was noticeably stronger than the regular Shaw in the neck. Output was boosted accordingly..

I'm also thinking of making pole magnet humbuckers with mixed alnicos. Your thoughts?
Not sure this will work as planned using separate mag poles instead of a bar.

You will get signal, but likely more noise as the humbucking function would likely be unbalanced.

Humbuckers work on the basis of equal and opposite coils and magnets. The coils are fed off the opposite polarity ends of the same bar mag, so they are equal in strength and opposite polarity.

Pole mags would lack this magnetic bridge between the coils, so I would imagine they would be noisier.

Different strength mags would give you a more of a single coil, unbalanced sound, but again, more noise is the trade off.

Same thing happens with offset coils in a normal bar magnet humbucker...

No reason you can't have fun with it though!

No law against experimenting...
 

DarrellV

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I think Fender Range Humbuckers were pole magnet pickups.
So were the P-bass pickups.... So there you are.
But I'm pretty sure the mags strength and type were the same, and the coil geometry was as close to the same as they could get it.

My concern was more toward the mismatched magnet builds.

And just that they would likely be noisier, but it would change the sound of them as well.

Possibly in pleasing directions.

Somebody in here did an offset winding mod on a set of 57 classics a while back by changing the coil out with one from a different make of pickup.

He loved the sound of it afterwards....
 

Al Walker

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I figured that they could be coil split with different results for each coil and the humbucker mode would be like a miss matched coil humbucker. Like an original PAF. Although These would definitely not sound that much like a PAF
 

cooljuk

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Yes, you can make a humbucker with rod magnets, instead of a bar magnet, and you can use any combination of rod type magnets you like. It'll work and be noise canceling. Just keep one coil all South up and the other all North up. Stronger magnets will have much denser flux and those strings near them will be magnetized more greatly and produce louder signals.

Consider using a steel or iron bar in place of the typical bar magnet to act as a pole shoe. Or, just try both ways. You'll get a very different sound each way.

Keep in mind, when you mix magnet types in close proximity, the stronger ones can interfere and overtake the weaker ones. You'll probably have no issues mixing A4/A5 types OR A2/A3 types but if you start using something like A3 and A5 in the same pickup, you may have some issues, depending how you orient them and where you locate them in relation to each other. In a P-90, for example, this would be problematic as the magnets face each other in opposing directions.
 

Al Walker

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cooljuk, Thanks for the info. Where would you get a steel or iron bar for a pole shoe?
 

Antigua

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OK, so, I'm experimenting with some pickups I have hanging around. Just for fun. Can you put alnico pole magnets over a bar magnet? Alnico 3 over alnico 5, alnico 2 0ver alnico 5, or other combos. What is the result. I'm also thinking of making pole magnet humbuckers with mixed alnicos. Your thoughts?
Thanks.
The steel pole pieces that come stock in a humbucker have a higher magnetic permeability (and they have to in order to work), but a side effect of that is that it increases the inductance by a good amount, lowering the resonant peak. AlNiCo is much less permeable (it doesn't need to be permeable to function, since it's already a permanent magnet) so replacing the steel slugs with AlNiCo will decrease the inductance, and therefore increase the resonant peak, giving you more treble. So if you take a SD '59 and replace the steel pole pieces with AlNiCo, the presence of the pole piece magnet won't be the only difference, it will have different electrical values as well.

The property of the metals in the core are more important than the metals that are outside of the coil, because the magnetic flux is most highly concentreated in the coil core, so replacing the bar magnet with a piece of steel would also increase the inductance, but to a lesser extent, since it is outside of the core. Once the pole pieces are AlNiCo, the presence, or lack of, a bar magnet underneath becomes more trivial, because the AlNiCo pole pieces will have a much lower permeability than did the steel poles, and that high permeability is required to conduct the magnetism (or lack of) up towards the strings. So where as the steel pole pieces can be thought of as "helpers" to the bar magnet below, the ALNiCo pole pieces are more independent, and will do whatever they're going to do.

If the pickup is bright to begin with, this mod will make it brighter to some extent, so I'd suggest trying this with a pickup that is a little hotter/darker to begin with.

When placing the AlNiCo pole piece and bars near eachother, make sure they're wanting to attract and aren't being forced together (north on north, south on south) because that will actually weaken the permenent magnetic field of the AlNiCo, and might require that you have to charge them up again. There's a decent magnetometer called the WT10A on Amazon that can both assure the magnet orientation and inform you how strong the magnetic field is as you tweak things.
 
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cooljuk

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cooljuk, Thanks for the info. Where would you get a steel or iron bar for a pole shoe?
You might be able to find flat bar stock in the right width / height online, but it will probably come in 3' lengths or longer.

You don't have to be fancy. Find some low carbon steel scrap somewhere and cut it to size with a bandsaw, hacksaw, or shape it with an appropriate belt grinder. Just don't heat it up to the point that it changes color (keep it cool) and you'll probably be good.
 

freefrog

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OK, so, I'm experimenting with some pickups I have hanging around. Just for fun. Can you put alnico pole magnets over a bar magnet? Alnico 3 over alnico 5, alnico 2 0ver alnico 5, or other combos. What is the result. I'm also thinking of making pole magnet humbuckers with mixed alnicos. Your thoughts?
Thanks.
The result will necessarily depend on the parts actually involved but IME, replacing steel poles with AlNiCo is a possible occasion to experiment a paradox.

It certainly gives a pointier resonant peak and more high frequencies… but as it gives a greater sensitivity to the transducer, it makes it able to enhance the bass range, widening the bandwidth of the played guitar and giving it a lower “acoustical” Q factor once the instrument amplified.

That’s why for example the 3 bars graph of a Firebird style pickup (with 2 AlNiCo bars instead of the poles) shows more bass than the EQing graph of a mini-humbucker (with steel poles and bar in the coils above 1 bar magnet): https://www.seymourduncan.com/pickups/guitars/other-guitars?meta_params=type=Mini Humbuckers&solo=1&post_t=product-pickups&taxonomy_slug=other-guitars&taxonomy=pickup-types&order_by=

The mini-hb with steel bar and screw poles DOES have a lower resonant peak (a lower electrical Q factor) and more inductance... but being less sensitive, it actually reproduces a narrower and pointier bandwidth (with a higher acoustical Q factor).

I had posted a long answer about that in a previous topic about steel vs AlNiCo cores, but I’ve cancelled it because it was in a sterile argumentative context.

I can repeat it in this thread, as a simple testimonial about the experiments done here (we've swapped more than once steel cores and magnets in mini-hb / firebird transducers or Guild LB1 coils). :)

Let us know what is the result for you with AlNiCo poles AND bar mag: pickups being falsely simple devices, your experience might be totally different and will necessarily be instructive for us other members. Thx!
 
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